The invention relates to a power generator unit composed of a drive motor and a generator, particularly composed of a synchronous generator and a diesel engine, pursuant to the preamble of claim 1.
In the German Offenlegungsschrift 3009279, a generator that can be driven by a vehicle drive system is described, where the generator is structured as a heteropolar generator, the rotor of which is attached to the flywheel of the drive system, and where permanent magnets are provided to excite the generator, at its stator. In this connection, the voltage is generated in a winding of the stator, which is attached at the housing of the drive system, around the rotor in this drive system, formed with the motor vehicle engine, the rotor complements the flywheel of the engine. Its cooling system serves indirectly also to cool the generator.
It is a disadvantage of the known motor/generator unit that it takes up a large diameter, since its rotor is built up on the outside circumference of the flywheel; in spite of the fact that a motor and a generator are built together, no simplification of the construction, in the sense of a reduction in the number of components, is achieved. Rather, this involves the installation of a generator into the specially adapted gear housing of an engine, which must be sized with corresponding dimensions in the radial direction. Because of the limited volume available inside the gear housing, particularly in the axial direction, the electrical output of the generator is limited to the requirements of an on-board network in a motor vehicle.
A power generator unit as stated initially, which is furthermore combined with a pump unit, is described in the German patent DE 19721527. The rotor of the generator, which is attached at the crankshaft, forms the flywheel of the motor, at the same time. A coolant flow generated by the pump unit brings about cooling of the generator. Motor cooling is not described.
In contrast, the present invention is based on the task of achieving the result, in a power generator unit of the type stated initially, in terms of its design, that because of the combination, fewer components are needed, i.e. components can be used in multiple ways, and that the construction volume of the generator is low, both radially and axially. In addition, a simple method of construction is supposed to be implemented, with which the problems caused by bending of the crankshaft are eliminated and where cooling is performed in simple manner.
The aforementioned task is accomplished, according to the invention, with the characteristic of claim 1. In this connection,
a) the flywheel of the diesel engine is replaced by the rotor of the generator, which in turn is built onto a fan wheel that in turn is flanged onto the crankshaft of the drive motor, at its face;
b) the stator is structured as a package of iron sheet metal, which bears the rotor windings;
c) the rotor is structured as a package of iron sheet metal, which bears the permanent magnets to generate a rotating magnetic field.
In this connection, the fan wheel provides for cooling of both the generator and the engine, in efficient and space-saving manner.
The sheet-metal construction of the rotor and the stator allow a method of construction of the generator that particularly saves volume.
It is advantageous if the rotor of the generator, which is designed as an external rotor, is structured in such a way that it possesses the full momentum of inertia of the flywheel that would otherwise be required on the motor side. This means that on the one hand, the rotor can be sized with the mass momentum of inertia of a flywheel which would otherwise be present, and on the other hand, that the momentum of inertia that is required for the motor, and is usually provided by a flywheel, for example to guarantee that the motor can be started by hand, is available to the motor.
It is furthermore advantageous in such a combination of rotor and flywheel that it easily adheres to the flicker fusion threshold.
If one assumes that a goal of the present invention is for the radial dimension of the motor-side housing flange not to be exceeded by attaching a generator housing, which limits the circumference of the rotor, its axial dimension is determined either according to the mass momentum of inertia required for the flywheel, or according to the design of the generator as required for power production. Its active magnetic mass requires a certain size for magnetic field generation in the generator.
A further decrease in size of the construction volume of the motor/generator unit results from the fact that the rotor is installed directly at the fan wheel of the motor, advantageously within its ring part that carries the blades. Because of the resulting structure of the rotor as an external rotor with a relatively large diameter, a particularly high degree of utilization of the obstructed volume is obtained, at an extremely short axial construction length.
An advantageous attachment of the stator consists of having it screwed on multiple times at the circumference of an inside ring of the generator housing lid, by means of stator screws that are passed through bores in its sheet-metal package and secure the sheet-metal package together. It is particularly practical, in this connection, that the stator screws are inserted through spacer sleeves between the stator sheet-metal package and the inside ring, and are secured between the inside ring and the side of the stator facing away from it. In this way, the complicated process of mounting the stator centered on a shaft, for example, is eliminated.
Furthermore, it is provided that the rotor is screwed on multiple times at the circumference of the fan wheel, within the ring part that carries the blades, by means of clamping screws that are passed through bores in its sheet-metal package and secure the sheet-metal package together. It is particularly practical, in this connection, that the damping screws are inserted through support sleeves between the rotor sheet-metal package and the fan wheel, and are secured between the fan wheel and the side of the rotor facing away from it.
Both with regard to the rotor and with regard to the stator, this makes it possible to implement a particularly simple method of attachment, i.e. mounting, and significant cost advantages are related with this.
In a cost-saving embodiment, it is provided that several attachment screws that pass through the entire housing length, arranged distributed over the circumference, closely within the cylinder mantle of the generator housing, are provided, which are screwed onto a motor-side connection housing, on the one hand, and onto the generator housing lid, on the other hand.
Additional cost savings result from a particularly simple structure of the generator housing as a thin-wall cylinder mantle, preferably made of sheet metal, where the generator housing is secured in place between the connection housing and the generator lid, with both faces, over a flat area.
It is practical if a protective hood of the generator housing lid on the outflow side is also made of sheet metal, and attached to the generator housing lid by means of screw bolts that extend the attachment screws for the generator housing.
Inside the protective hood, a rotary magnet can be provided as a voltage regulator. It is advantageous in this connection if its yoke, which carries an exciter winding, is attached to the generator housing lid. In case of an electronic voltage regulation, which does not require any noteworthy space, a protective hood with a particularly flat structure can be used, with a corresponding reduction in the length of the generator part.
With the present invention, it has become possible to create a motor/generator unit with which cost savings as compared with conventional comparable units of up to 50% are made possible, on the side of the electrical technology part, for a rated output of approximately 10 kVA, for example. It is particularly suitable as a network frequency power generator with low output and a small construction size.